Shock absorbing arrangement



April 13, 1965 W. H. PETERSON 3,178,035

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VINE/NAAM H. PETERSON United States Patent O 3,l7,l35 SHOCK ABSRBlNG AMANGEL ENT William H. Peterson, Homewood, lll., assigner to Pullman incorporated, Chicago, lll., a corporation of Delaware Filed May 1, 1963, Ser. No. 277,190 lil Claims. (Cl. ZlS-S The present invention relates to shocl: absorbing arrangements and more particularly to shock absorbing arrangements employed in railway vehicle construction.

rl`he shock absorbing arrangements employed in railway vehicles .serve to protect the structure land the lading supported by the vehicle from the impact forces to which the vehicle is subjected during use. .in the standard railway car this is accomplished by means of draft gear associated with the couplers. However, design limitations are generally such that the travel of the draft gear must be maintained relatively short, say for example a total travel of about ve inches, and thus does not provide anything approaching reasonable protection for a wide variety of category of ladings. Such catagories of lading may include those which are compactable and subject to permanent deformation upon impact. This category of lading may be designated as resilient lading in contrast to ladinU which is rigid and not readily subject to damaging deformation. It is the resilient lading which is the most susceptible of being damaged by the cushioning inadequacies of draft gear.

ln providing protection for both rigid and resilient lading long travel cushion underframe cars arranged in accord-ance with my Patent 3,993,436, granted October l0, i961, have proven to be particularly satisfactory. These cushion underframe cars employ a sliding sill mounted on the underframe for lengthwise movement of the car. The sliding sill supports the couplers on the ends thereof. A cushion device having the closure characteristics described in said patent is interposed between the underframe and the sliding sill for interaction therewith and is operative to achieve the desired lading protection by functioning with the principles of said patent. rthe cushion device, and also the sliding sill, will thus have a travel in the range of from about 20 to about 40 inches in either direction and the cushion device will have the force travel closure characteristics specified in said patent.

The sliding sills as above described are slidably supported on the underframe but otherwise are structurally detached from the car body. Under these circumstances, the sliding sill must be capable of withstanding without failure the loads imposed thereon by impacts at the couplers encountered during use. In this connection it should be mentioned that the compression loading which is iinposed on the sliding sill, as during humping and switching of cars or run-ins of slack during train operation, is considered to be critical and under certain conditions may tend to cause failure of the sliding sill by bending or in compression.

Heretoforc, sliding sills employed in railway cars have been reinforced in order to withstand the loading imposed thereon. The reinforced structure has the primary disadvantage ot increasing the overall weight of the car. Moreover, the reinforced structure of the sliding sill is such that it cannot be readily accommodated within the limited space provided by the conventional Z26 type center sill which is generally employed in a conventional uncushioned car construction.

ln my US. patent application Serial No. 196,320, tiled May 2l, i962, there is disclosed a cushion underframe railway car construction which embodies a sliding sill construction and cushioning arrangement for protecting a sliding sill so that the latter may be formed of minimum cross-sectional area and be accommodated within the conventional Z-26 center sill structure. This is accomplished generally by employing a sliding sill construction including ena-to-end sections movable lengthwise relatively to each other between a vertical spaced position assumed during normal operations, a contracted buff position, and an extended draft position assumed upon buitr and draft respectively. This sliding sill construction obviates the necessity of draft gears at ends of the sill for mounting the couplers, and utilizes a single resilient shock absorbing unit disposed to coact upon impact causing the sill sections to be moved to either the draft or buit positions thereof to absorb a portion of the shock impact. The single resilient shock absorbing unit is disposed so as to relieve the stresses imparted through the length of the two sections of the sliding sill. Furthermore, the lading protection cushion device, which preferably is of the type disclosed in said Patent 3,063,436, and which is disposed to interact between the sliding sill and the car body, and serves to provide ladingv and car body protection, is arranged so that an increment of its full travel is utilized at least upon relative movement of the sill sections to their buit position to protect the sill itself. The sliding sill sections, the shocl; absorbing unit which reduces the stresses through the length of the sliding sill, and the lading protection cushion device are associated such that he energy absorbinU capacity `of the sill shock absorber unit and the underframe cushion unit are simultaneously employed to relieve the stresses through the sliding sill as the sill sections move to their limit positions assumed upon a buff or draft impact. Thereafter, the sill sections are movable in unison relative to the underframe so that the full travel of the lading protection cushion unit is employed to protect the lading supported on the car body.

ln Ithe cushion underfrarne arrangement described above utilizing the lend-to-end sectioned sliding sill wherein a resilient shock absorbing unit and a portion of the travel of the lading protection cushion device is employed to achieve sliding sill protection, the closure characteristics of the shock absorbing unit and cushion device make these devices suiiiciently responsive at relatively low impact speeds that the sill sections are moved relatively to each other. This may result in an undesirable run-in and runout ot slack during normal train action.

Such run-in and run-out of slack may also occur in draft gears, especially those of the type employed to achieve a greater degree of lading protection and utilizing travels in excess of the 2 to 3 inches normally employed.

Accordingly, it is an object of the present invention to provide a shock absorbing arrangement for absorbing a portion of the shock of impact at the couplers in a manner minimizing the run-in and run-out of slack during normal train action.

This is accomplished generally by the provision of a shock absorbing larrangement including a shock absorbing device associated with the coupler carrying structure of the car which is constructed such that no .travel of the unit occurs at the relatively low impact or coupler forces encountered `during normal train acti-on and is responsive and movable to travel upon impact forces of higher magnitude. The impact coupler force at which the shocl: absorbing unit is operative is selected such that the impact forces below the selected value are readily withstood by the car structure and such that the unit upon becoming` operative is adequate to provide cushioning over its full length of travelV that is adequate to maintain impact force level below that causing structural damage.

In carrying out the present invention the shock absorbing device referred to immediately above is constructed to provide a high impact energy absorbing capacity and comprises essentially a friction wedge energy dissipating assembly including a plurality of longitudinally movable and opposing -pairs of friction shoes having .opposed sloped friction faces accommodating therebetween transversely movable friction wedges which are biased by means of pre-loaded springs exerting a force on the wedges,` precluding relative movement of the wedges and friction shoes until the impact force applied on the unit is greater than that applied by the preloaded springs; whereupon the unit is rendered operative to'travel .and absorb sufficient energy to protect the structure withwhich it is associated from damage resulting from the impact force.

It is another object to provide a shock absorbing device constructed and arranged to include a plurality of lengthwise spaced and longitudinally movable friction shoes having opposed sloping friction faces accommodating coacting friction wedges therebetween and including predetermina-tely loaded spring means biasing the friction wedges to prevent the device from being operative until an impact Vforce overcoming the biasing force is applied.

' Another object of the invention is to provide a friction wedge shock absorbing device constructed and arranged -to have substantially constant resisting force during each increment of travel thereof.

Still another object is` to provide a friction-wedge shock absorbing device constructed and arranged to have substantially constant resisting force during each increment of travel thereof and to be inoperative untilV an impact force of a selected magnitude is applied thereon.

It is still another object to provide a shock absorbing device for use in a sliding sill of a cushion underframe railway car for protecting the sliding sill from damage resulting from impact wherein the shock absorbing device is constructed and arranged to be operative at irnpact forces in excess of those encountered during normal train action so as to minimize the run-in and runout of slack.

It is still another object to provide a shock absorb ing device for use lin a cushion underframe railway car for protecting the sliding sill from damage resulting from impact wherein the shock absorbing device is constructed and arranged to include a plurality of lengthwise spaced and longtiudinally movable friction shoes having opposed sloping friction faces accommodating coacting friction wedges therebetween and having predeterminately spring means biasing the wedge means to pre-V vent the device from being operative until the impact force on the sillV is a selected magnitude substantially greater than that encountered during normal trainraction.

It is still a further object to provide a sliding sill of a A cushion underframe railway car wherein the sliding sill is formed in end-to-end sections movable relatively to each other and to the underframe and employing a shock Y sill and the sliding sill structure of the railway car shown Y in FIG. 1. Y

FIG. 3 Yis a fragmentary top sectional view taken through the underframe and showing the relative positions ofthe components in the neutral position.

' FIG. 4 is a cross-sectional view taken substantially along the lines 4 4 of FIG. 3.

FIG. 5 is a cross-sectional view taken substantially along the lines 5-'5 of FIG. 4.

i FIG. 6 is a cross-sectional view taken substantially along the lines 6 6 of FIG. 4.

FIG. 7 is a fragmentary isometric view of the .stationary sill and the sliding sill disposed therein with some of the parts being broken away to show underlying details of structure. Y

FIG. 8 is a fragmentary schematic elevational crosssectional view similar to FIG. 3 showing the relative positions of the sections of the sliding sill to each other and to the center sill in the neutral or normal position thereof.

FIG. 8A is afragmentary schematic elevational view showingrthe relative positionof the components of FIG.

8 where the magnitude of the impact force applied on the sliding 'sill is insuflicient'to activate the shock absorbing unit but results in activating the cushioning unit interacting between the sliding sill and stationary sill.

FIG. 9A is a fragmentary schematic elevational `crosssectional View showing the relative position of the sections of thersliding sill to each other and to the stationary center sill upon impact to the left sliding sill causing closure of the Vshock absorbing unit and with the right sill section restrained against movement to the Y right.

FIG.V 9B is a fragmentary schematic elevational view similar to FIG. 9A but showing the relative positions of the components when the right end is not restrained.

FIG. 10A is an elevational cross-sectional viewsirnilar to FIG. 8 showing the Vrelative positions of the comlar to FIG. 8 showing the relative positions of the coniponents when a draft force is applied on the left sill Siection causing the shock absorbing device to partially close with the right sliding sill section restrained against movement to the left. Y

FIG. 171B is an elevational cross-sectional view similar to FIG. 11A with the conditions ofthe force impact being the same but with the right sill section unrestrained.

FIG. l2 is a vertical cross-sectional view of one form of shock absorbing device embodying the present invention shown inthe neutral or extended position.

FIG. 13 is a vertical cross-sectional view similar to FIG. 12 but shown in the contracted position thereof.

FIG. 14 is an isometric view of a shock absorbing device illustrated in FIG. 12 partially in section but showing only two sets-of friction shoes coacting with two friction wedge assemblies. n

FIG. V15 is an Visometric view of a shock absorbing device with a single set of friction shoes coacting with a single friction wedge assembly. Y

1FIG. 16 is an isometric view of a friction wedge assemb y. Y

FIG.` 17 is a top plan sectional view of the draft Vend of a center sill showing a second embodiment of a shock absorbing device employed as a draft gear.

FIG. 18 is an isometric view of a'shock absorbing devide partially in section embodying the principles -of the device shown in FIG. 17 but showing only two sets of friction faces and two coacting friction wedge assemblies.

FIG. 19 is a vertical cross-sectional view taken through the shock absorbing device employed in FIG. 17 showing the device inV its extended position.

FIG. 20 isa vertical cross-sectional view similar to FIG. 19, but showing the device in its contracted position.

y FIG. 21 is an exploded view of the friction wedge unit.

FIG. 22 is an enlarged fragmentary vertical sectional view of onerset of friction wedge units in the normal Y position and showing in phantom lines the contracted position thereof.

Referring now to FiGS. 1 7, the cushion arrangement of the present invention is shown illustrated in an underframe itl of a railway car 1l. The underframe includes a center sill 12, the usual holsters 13, cross bearers lid, end sills i6, and side sills i7. Mounted on the underframe itl for lengthwise movement thereof is a sliding sill 18 and operatively disposed between the latter and the underfrarne 19 for interaction therewith is a hydraulic cushion device 1i? which serves to provide lading and car body protection.

As best shown in FIG. 7 the stationary center sill l2 may be a standard Z-26 center sill including a horizontal web 21 from either side of which there extends vertical webs 2,2 terminating at their lower ends in outwardly extending horizontal ilanges 23. The sliding sill is disposed within the center sill enclosure 2d and slidably supported therein by means of channel member 26 detachably secured along the underside of the stationary sill 2-2 across the horizontal iianges 23. To facilitate sliding movement of the sliding sill l there are provided wear plates, not shown, xed in complementary relationship along adjacent surfaces.

As shown, the sliding sill l is formed into two endto-end lengthwise movable sections 27 and 2d. Each of the sections Z7 and Zd may be formed from columns of H-section. The center sill i8 is disposed within the center sill 12, so that the horizontal web 29 thereof lies in the close proximity to the coupler line of draft and the..

33 thereon. The coupler 33 is attached for swing moven ment by way of a coupler pin 34 carried by a coupler support 36 disposed between a tie plate 37 fastening the housing 32 to the sliding sill 1S and stops 3S fixed in the housing 32. For a more detailed description of the coupler housing 32 and mounting structure reference is made to the aforementioned Peterson application 196,320.

As heretofore discussed, in conventional uncushioned railway car structure draft gears are conventionally ernployed to mount each of the couplers on the sill for the purpose of protecting the structure of the car body. However, in the cushion underframe railway car as clearly illustrated by the above described structure, the sliding sill i8 is substantially detached from the car body so that the impact force at the couplers 33 is assumed almost entirely by the structural components of the sliding sill and the resulting stresses are not distributed through the other structural components of the car body as in conventional uncushioned railway car construction. It is for this reason, namely, for relieving the stresses through the sliding sill, that it has been the general practice to provide sliding sills with draft gears associated with each of the couplers. As more fully to be set forth hereinafter, the structure of the present invention does not require a draft gear at each end thereof.

As shown in FIGS. 2, 3, 4 and 7, the cushion device i9 for achieving lading protection is disposed in a cushion pocket formed in the sliding sill section 23. rhe cushion pocket may be formed as a weldment including transversely spaced vertical plates 4l lixed at one end to the inner ends of the vertical webs 31 of the H-column. Disposed across the vertical plates el is a horizontal web plate 42 which is spaced from the horizontal web 29 of theH-colurnn to receive the extended length of the cushion device 19. Fixed across the upper ends of the vertical plates 41 is a top cover plate d3 having longitudinally extending slots da formed in each end thereof for accommodating stop lugs 4S and d6 iixed to the stationary center sill 12 and which engage and coact with the follower plates 47 and 4S respectively of the cushion device 19 as more fully to be explained hereinafter. Similar stop lugs 45a and lea spaced complementary to the stop lugs 45 and do are lixed to the sliding sill supporting channels 9,6. A bottom cover plate 4% having longitudinal slots da for accommodating the stop lugs Sa and lea is detachably secured across the bottom of the pocket 39 by means of bolts fastened through downwardly depending flanges 5l. on the bottom cover plate it and vertical plates dll.

T he cushion device 19 may be a hydraulic unit which is operative upon contraction caused by the application of impact thereto at the followers to provide a force resisting contraction and thereby to afford protective cushioning, rl'he cushion unit l is preferably of the type disclosed in said Patent 3,003,436, and has a total closure travel in either direction from ythe neutral extended position shown inthe range of lfrom between about 20 to labout 40 inches, preferably 3) inches, and unit i9 is preferably arranged to provide during such ltravel a substantially constant resisting force during each increment of travel, from the extended neutral position, such that the magnitude of the forces acting on the lading as a result of the impact is maintained at levels below that causing damage to the lading. The cushioning means or device i9 illustrated includes a spring means til disposed between the follower plates d? and Lid for returning the device to its normal extended position after the impact Iforce has been dissipated.

Fixed to the sliding sill section 2S for movement therewith are a pair of yoke assemblies or members 52 disposed on opposite sides of the horizontal web `29 and plate il?, and overlying the other sliding sill section, The yoke members 52 each include straps S3 fixed to the vertical webs of the section 2S along one end portion thereof lie at the end of the cushion pocket for engagement with the cushion follower plate 43. The terminal ends 5d, thus serve as stops. The Alengths of the straps 5s extending beyond the end of .the sill sections 2b are spaced from the inner walls of the vertical webs 3l and the horizontal web Z9 of the sliding sill section 27 to permit free relative movement of the sections in a manner more fully to be explained hereinafter.

Extending across each of the oppositely disposed pairs of straps E53 inwardly of the ends thereof is a horizontal buit key Se in lthe l`form of a plate. Extending across the ends of each of the straps S3 and forming the bight portion` is a draft ykey 57 also in the form of a plate. The buff and draft keys Se and S7 are spaced lengthwise so as to embrace a shock absorbing unit 5S mounted in an opening 59 formed 'in the sill section 27.

lFixed `on opposite sides of the horizontal web 29 of the section Z7 for movement therewith are pusher bars rthe terminal faces 62 of the attached end of each of the bars el in in alignment 4with the inner edges of the cushion receiving opening E?. The pusher bars di are arranged to extend` into the sill section 23 and are disnosed in spaced relation with the horizontal web plate l2 thereof and in the neutral position of the sill sections 27 and 28 .the terminal ends da extending into the sill section 2S albut the cushion follower' 4S as shown, for example, in FlG. Il.

The shock absorbing unit S3, as shown in particular in FlGS. l2 through 16, includes generally a plurality of friction shoes 63 and 66 having disposed therebetween :friction wedge .assembly 64. The sloping surfaces of -friction faces 67 of the shoes 63 are sloped outwardly relative to a plane normal -to the longitudinal plane passing through the center of the assembly. As shown the inboard and outboard end friction shoes 65 are each formed with two yfriction faces e7 on the inner sides thereof. The intermediate shoes 63 are formed with friction faces 67 on Vboth sides thereof arranged in opposing relationship to lthe friction faces 67 on an adjacent one of the friction shoes 63 or inboard and outboard shoes 66.

The friction wedge assemblies o4 disposed between the friction shoes 63 are each of similar construction and include wedge blocks eil of trapezoidal section of which Y Overcome.

the friction faces 69 thereof are sloped complementary to the opposing friction shoe faces 67 so as Ito maintain the central longitudinal plane of the assembly 64.

Support-ing the wedge blocks 68 are frame members V70 to the opposing end walls 7-1 of which there is suitably fixed a resilient means 72 biasing the respective wedge blocks 68 toward each othersuch that the blocks 63 are in abutting relationship along the central longitudinal plane. In this position the wed-ge blocks 63 are operative to maintainrthe friction shoes 63 at the maximum horizontal spacing t shown in FIG. Y12.

In accordance with the `present invention the resilient biasing means 72 is selected to apply a predetermined biasing force on the wedge blocks 68 and to maintain the assembly inoperative until the impact force applied thereon is of a'certain selected magnitude tending to cause damage to the structure being protected thereby. That is to say the shock absorbing means is maintained inoperative until the magnitude of the impact force is above that which tends to create damage to the sliding sill 18. In'

the embodiment of the invention disclosed in `FGS. 12 through 16 the resilient biasing means 72 is in the form Vof a resilient rubber pad. The rubber pads 72 are bonded along one side to the respective frame end walls 71 and along their other side to the respective Wedge blocks 68.

As shown in FIGS. l2 to 16, the friction faces 67 and 69 are formed as inclined plane having a fixed angle of inclination, a, and the friction faces 67 and 69 of the friction shoe 63 and wedge block 68 are formed to provide a substantially constant coefficient of friction for the full length of sliding movement of the wedge blocks '66 on the'friction shoes 63. Knowing the angle of inclination a and the coeflcient of friction u the desired resisting or biasing lforces of each of the'springs 72 of the cushion pad assemblies may be obtained from the relationship [7:51a tan'a-l-l Y tan a-u wherein F is the impact force above which the sliding sill structure is subject to stresses tending to-cause damag and S is the biasingspring force.

Thus, when the shock absorbing assembly S is subjected to a shock impact at either of the end shoe follower F, the biasingforce S of the springs or rubber pads' 72 is away fromreach other and the friction shoes 63 traveling longitudinally toward each other to the position shown in FIG. 13. As the device is operating a portion of the energy of the impact is dissipated as heat at the friction faces 67 and 69 and a minor portion is absorbed by the compression of the rubber springs 72. The total energy absorbing capacity of the shock absorbing unit 58 is of course determined by the area under the force travel relation of the resisting force and the length of travel from the fully extended position shown in FIG. 12 to the contracted position in FIG. 13. The travel of the unit may be changedby either increasing or decreasing the number of friction shoes 63 and wedge assemblies 64 so that the total of the individual travels t as shown in FIG. 12 is 'equal the total desired travel. Thus,` the units shown in FIG. 15 having only two friction shoes 63 and a single wedge assembly 64 has a total travel of V2t while the units illustrated in FIGS, 12 and 14 have travels of 19t and 4t respectively.

As above explained, a Yportieri of the impact energy is absorbed by the compression of the spring pad 72. Inherently, springs of this type when compressed provide a variable resisting force Vof increasing magnitude which results in the unit having a force travel closure characteristie wherein the resisting force is of graduallyrincreasing magnitude. p

In FIGS. 17 through 21 there is shown a second embodiment of a friction Wedge shock absorbing unit 258 This results in the wedges 68 moving laterally wherein the shock absorbing capacity is maintained at a maximum by constructing and arranging the unit such that the resisting force thereof is maintained more nearly constant for each increment of travel thereof. This is accomplished generally by varying the angle of inclination of the sloping friction surfaces to compensate or correct for the increase in force resulting from the compression of the rubber pads.

' As above described in connection with the embodiment ofthe shock absorbing unitV disclosed in FIGS. 12 through 16, the resisting force S of the rubber pads F increases as the latter is compressed such that the relationship Y tan a-u is notmaintained constant over the full length of travel of the device. inasmuch as the coefficient of friction u of the friction faces is fixed at a substantially constant value and the impact force F is, of course, independent of the structure employed, only the angle of inclination of the friction faces may be varied.

To this end the shock absorbing unit S includes a plurality of friction lshoes 263 in spaced relationship and between which there are disposed wedge sub-assemblies 264.

shoes are arranged to slope toward the other so as to provide a wedge block accommodating space therebetween. The wedge block sub-assemblies 264 are each of similar construction and include the wedge blocks 268 disposed Y on opposite sides of the longitudinal plane passing through the unit and have friction faces 26S. sloped complementary to the friction shoe friction faces 267. Fixed to the outer side of each of the wedgeV blocks 268 is one end of a V.resilient spring means 272 of which the other end is xed to the inner end Wall 271 of a rectangular frame member As shown, the resilient spring 272 means includes a Y plurality of rubber pads 272:1 separated by metallic plates 27217. The spring means 272 is selectedV to provide an initial resisting force rendering the device inoperative until a predetermined impact force is applied thereto by use of the formula set forth above.

To maintain the resisting force of the cushion friction wedge unit 258 more nearly constant as the rubber springs are compressed between theV extended preloaded position shown in full lines and the compressed position shown in phantom lines in FIG. 22, the friction faces 267 and 269 are formed as the circumference of circular arcs. The center of the circular arcs are determined such that the initial angle of inclination a and the nal angle of inclination b (FIG. 22) corresponding to the initial position and fully compressed positions, respectively, of the rubber pads 272 .are such that as'can be seen in the expression for cushion force,

F: Su tan a+ l tan a-u when the force on the rubber pads, S increases to its fully compressed value and with a given friction coefcient u, the angle a is changed to a selected lesser value b so that F at full cushion closure is essentially the same as it was at the beginning of closure. In this manner the resisting force of the shock absorbing device is maintained more nearly constant for each unit of travel thereof so thata maximum energy absorbing capacity is achieved at a minimum force.

'Ihe wedge blocks 268 are each formed in two wedge members 268e and 268beach having an arcuate friction surface or farce 269 formed thereon. The wedge member 268a is formed with space hinge ears 274 which are turnably nested Within a complementary receiving groove 276 formed in the other Wedge member 268. Extending from the wedge member 268b is a hinge leaf 277 which is received within the cut-out 273 between the hinge ears 274i. Mounted in the hinge ears 274 and extending through an opening in the hinge leaf 277 Vis a hinge pin 231. This hinged construction of the wedge bloclc 263 permits the friction faces 269 thereof to remain in full surface contact with the shoes friction faces 267 for the full extent of relative movement therebetween.

ln operation, therefore, upon application of shock having impact to either of the end follower surfaces 266 of the friction shoes 263, resulting in an impact F causing the rubber springs 272 to be compressed, the friction shoes 253 are longitudinally compressed and the friction Wedge blocks 2-68 are displaced laterally against the force of the rubber spring 272. During lateral displacement of the friction wedge block 263 the arcuate friction faces 269 on the wedge members 268e and 2682 remain in contact with the complementary arcuate friction faces 267 of the friction shoes 263 such that as the angle of inclination of the friction surface decreases from a to b there results an increase in the mechanical advantage which substantially offsets the increasing spring force so that a substantially constant resisting force is maintained throughout the length of travel of the shock absorbing unit The desired total travel of the shock absorbing unit 253 is obtained by using a suliicient'nurnber of friction shoes 263 and coacting friction wedges 26S such that the total sum of the increment travels is equal to the desired travel.

Either of the shock absorbing units 58 or 25S may be disposed in the opening 59 of the sliding sill section 27 depending on whether it is desired to utilize the gradually increasing resisting force travel closure characteristic of the unit SS or the substantially constant force travel closure characteristic of the unit 253. ln the illustrated cushioning arrangement for the purpose of explanation the unit 5S is employed for relieving the stresses imposed on the sliding sill structure. lt should be kept in mind, however, that the shock absorbing unit 258 may also be employed and that it coacts with the sliding sill structure in the same manner and differs from the shock absorbing unit :3S only in the manner in which the friction wedge faces 267 and the friction shoe faces 26@ thereof function to achieve the substantially constant force travel closure characteristics.

The shock absorbing unit S3 is disposed in the opening S9 of the sliding sill section 27 and supported on the web 29 by means of ear-like projections 3l formed on the upper' ends of the friction shoes 63 and frame 70. The shock absorbing unit 258 may also be provided with earlike projections Zbl. Engaging the follower surfaces 66 of the inboard friction shoes 53 are the ends of the pusher bars 6l which serve as stops and engaging the outboard follower surface 66 are stops 55 fixed to web 29.

ln the normal extended position of the sliding sill sections 27 and 28 as shown in FlG. S, the shock absorbing unit S8 is in its extended or inoperative position. The sill sections 27 and 2S are spaced apart a distance n and the cushion device l@ is in its extended position with the follower plates 47 and 43 engaging the respective underframe stops i5-25a and @eS-46a and also the sliding sill stops SS and 54 such that the sliding sill is maintained in a neutral position relative to the car body or underfrarne il. Also, the draft and bulf plates or keys S6 and S7 on the yokes SZ which are mounted for movement with the sliding sill section 28 are engageable with the outboard and inboard follower surfaces 66, respectively, of the shocl: absorbing device 53 and the pusher bars di fixed for movement on the sill section 27 engage at their fixed ends the inboard follower surface 6d and at its free terminal end 62a the follower plate d'7 of the cushion unit 19.

Assuming that the structure of the sliding sill l0 is such that it is readily able to withstand impact forces up to about 750,000 lbs. applied at the couplers without imposing failure causing stresses therein, and that the rubber springs 72 within the shock absorbing device exert a biasing force on the friction faces 67 and 60 thereof to render the device SS inoperative until the impact forces approaching the maximum stresses, say for example, between 300,000500,000, preferably 400,000, any application of an impact force at the follower surfaces 66 of the unit 5S above about 400,000 will cause compression of the device. Assuming further that the neutral spacing n of the sill sections 27 and 25 and the total travel of the shock absorbing device S8 are each equal to about 10 inches and that the travel of the cushion device i9 is about 30 inches in either direction, application of animpact force at the couplers will cause different actions depending on the conditions under which it is applied.

Assuming first that the car embodying the above structure is in a moving train line disposed other than at the end of the line and that the train action is such that a buff impact is applied at the left end coupler as indicated by the force arrow F in FlG. 8A, this force F is transmitted through the sliding sill section Z7, the shock absorbing unit 58 mounted on the latter and to the sliding sill section 28 via the yoke 52 fixed thereto and encompassing the shock absorbing unit 5S.

ln the event that force transmitted to the sill sections 27 and 2S at the shock absorbing device 50 is less than 400,000 lbs., the shoclc absorbing luiit Sil remains inoperative because the resilient rubber pads provide a biasing force on the wedge blocks 63 which applies a force along the friction faces 67 and 69 greater than the force applied therealong by the impact force. Thus, the friction shoes o3 remain stationary in an extended position and the buff keys 5o and draft keys 57 fixed to yolces 52 engaging the follower surfaces 66 of the shock absorbing unit $3 mounted on the sill section 27 serves to tie the latter to the sill section 2li via the yoke straps 53 fixed to the sill section 2d.

rlibe sliding sill l with the sections 2.7 and 2S maintained in their extended spaced relationship n under the influence of the shock force F applied thereto moves lengthwise relatively to the underframe il. During the movement to the right as shown in FIG. 8A, the pusher bars el fixed to the sill section Z7 and having their terminal ends o2 engaging the follower plates 66 and the horizontal stop plate 42 of the sill section 2d are operative to contract the cushion devices against the stop lugs a and de' vfixed to the stationary center sill l2 of the car body underframe ll. Contraction of the cushion device t9 operates to protect lading in accordance with Patent 3,003,436.

Assuming now that the car embodying the construction of the present invention is at the head end of a stationary line of cars and a bud impact force F (FIG. S) is applied to the left end coupler which is free. If the impact energy is of a magnitude such that the forces transmitted along the length of the sliding sill between the coupler ends thereof is less than 400,000 lbs. and does not create a compression loading tending to create sill damage, the shock absorbing unit remains inoperative so that the sill sections 27 and 2d remain spaced as shown. As above described, the shock absorbing unit 5S remains inoperative because of the pre-loading of the rubber spring pads 72 which compress when the force exceeds 400,000, whereby the yoke 52 encompassing the cushion device 5S and fixed to the sill section Ztl remains stationary.

As described above in connection with the running o1' moving car, the impact for F also tends to move the sliding sill l lengthwise of the underframe l1. If such lengthwise movement occurs, the cushion device 19 is activated as previously described. However, under some circumstances the cushion underframe car may be coupled to a stationary line of cars of standard construction and the mass of the latter may be such as to form in the nature of a solid abutment. Under these circumstances the sliding sill is restrained against lengthwise movement such that substantially no relative lengthwise movement occurs between the stationary underframe 11 and the sliding sl 1S.

V45 and 45a.

Assuming now that the impact force F is increased so that force transmitted to the shock absorbing device and at the yoke bui'f plates 56 via the sliding sill sections 27 and 28 is of magnitude of over 400,000 lbs. overcoming the biasing force of rubber pads l72 and is suiiicient to cause the device 58V toV be completely contracted, during this travel the full energy absorbing capacity of the shock absorbing unit is employed to protect the sliding sill 18.V

At the same time, the sill section 27 moves relatively to the sill section 28 until the adjacent ends abut as shown in FIG. 9A and the pusher bars 61 fixed to the moving sill section 27 are operative to compress the cushion units 19 against the sliding sill stops 55 and the underframe stops 46 and 46a. In this manner a portion of the travel of the cushion device 19 may be employed to the extent of the relative travel of the sill sections 27 and 28. Should the sliding sill be connected at its right end coupler to a line of cars forming in the nature of a stationary, abut- `ment, the sliding sill 18 is, of course, restrained against substantial movement relative to the stationary sill 12.

, When the force of impact has been dissipated the springs 40 of the cushion device 179 acting via the follower plate 45 abutting the pusher bars 61 and the'rubber springs 72 of the shock absorbing device are operative to restore the sill sections 27 and 28 to their neutral position.

In the event that the right end coupler is` not restrained against lengthwise movement, the cushion device 19 may complete its fulllength of travel (see FIG. 9B) through the action of the pusher bars 61 acting asV stop keys contacting the follower plate 48 and compressing the cushion device 19 for' its full length of travel against the stop lugs Inxthis manner the cushion device 19 is operative Vto perform its heretofore described cushioning functions. As above, when the impact energy has been dissipated the cushion spring 40 and the shock absorbing rubber biasing springs 72 or 272 are operative to return the sliding sill sections 27 and 23 to the neutral position shown in FIG.V 8.

It should be apparent that in the event the impact force transmitted to the shock absorbing unit is not of a magnitude causing full travel of the shock absorbing unit 58, the sill sections 27 and 28 travel toward each other from the neutral position to the same extent as the travel of the shock absorbing unit 58. The operation of the sliding sill 18 relative to the car body and the operation of the cushion unit 19 remains unchanged from that described above.

Should a bulf impact be applied to the right endof the sliding sill 1S it is, of course, apparent that the structure will function similarly to the buff impact applied at the left end described above with the exception that the movements of the sliding sill sections 27 and 28 and the cushion unit 19 relative to each other and the stationary sill will be toward the left rather than to the right.

Assuming now the conditions wherein the car is again,V

in a moving train line other than at the end thereof, and that during train action a draft force F is applied on the right end or left end of couplers of the sliding sill 28, this tends to pull the sill sections 27 and 28 apart. This causes the yoke draft keys 57 xed for movement with the sill section 28 to exert a force on the shock absorbing unit at the outboard follower surface 66 tending to compress the shock absorbing unit 58. Should the draft force encountered during train action be less than 400,000 lbs., the shock absorbing unit 58 which is operative only at impact forces above 400,000 lbs., remains extended and maintains the sill'sections 27 and 28 intheir extended neutral position, n, as shown in FIG.V 8. f

At the same time, the sill sections 27 and 28 in their extended neutral position, n, are slidably movable in unison in the direction of the forcer relative to the stationary' sill 12. VDuring this movement the respective stops 54 and 55 xed for movement with the sliding sill and abutting the cushion device follower plates 47 and 48 are operative to compress or contract the follower plates I2 Y Y Y 47 or 48 against the opposing one of the Vstops '45'4Sa or 46-46a fixed to the underframe. In this manner, the cushion device 19 is rendered operative to protect the underfrarne and Vthe lading supported thereon from damage.

Assuming now that the car is attached at its left coupler to a stationary line of cars and a draft impact force F is applied on the right end, as shown in FIG. 10A, this tends to move the sill section 28 to the right relativelyrto the car attached Ysliding sill section 27 so that a force is Y exerted by the yoke draft keys 57 on the shock absorbing follower surface 66 tending to compress the shock absorbing unit 5,8. If the force exerted between the draft keys 56 and the shockl absorbing units 58 is less than the selected force of 400,000 lbs., which causes the wedge blocks 68 to be displaced laterally against'the biasing force of the rubber pads 72, the friction shoes 63 remain in their extendsd position. In this manner, the sill sections 27 and 28 are retained in their spaced neutral position as shown in FIG. 8.

The shock impact force at the same time tends to cause the sliding sill sections 27 and 28 to move in unison to the right relative to the stationary sill 28. -In the event that the stationary line of cars at :the left end forms in the nature -of a -solid abutment, the sliding sill 18 is restrained from relative movement. However, if the sliding sill 18 -is not restrained as when the force `is such that the attached car mass is moved or the sill 18 is connected to sliding sills :of other cushion underframe cars, the sliding sill E8' slides lengthwise to the right relative to the stationary center sill 12. During the sliding movement the stops 54 fixed to the sliding sill .section 27 and contacting lthe follower plate 48 are operative to compress the cushion device 19 against the stops 45-4Sa Vfixed to the stationary -sill 12 such that the cushion device 19 is activated to protect the lading and car body.

Assuming now that an increased draft impact force F of over 400,000 lbs. is applied so that the force trans'- mitted to the outboard follower surface 66 of the shock absorbing device 58 by way `of the yoke draft key 57 is greater than the biasing force resisting compression of the unit 58 and is suiiicient to cause the device to be partially compressed a distance d as shown in'FIG.l 10A. During this partial travel d of the shock absorbing device 58 a portion of the impact energy transmitted through the Vsill is absorbed as hereinbe-fo're described. At the same time the left sill section 28 movesl relatively to the right sill section 2'7 from .the neutral position a distance corresponding to the length of travel of the shock absorbing device 58. In connection with the travel of the Vshock absorbing device 58 it should be noted that as previously discussed, therdraft impacts are generally of lesser magnitude than the buff impacts so .that generally the full travel and accordingly the full energy absorbing capacity of the shock absorbing device58 is not util-ized or, in fact, required.

During the compression of the shock absorbing unit 58 and the movement of the sill `sections 27 and 28 outwardly a distance d from the neutral position, the pusher bars 61 are displaced'rout of contact with the follower plate 48 of the cushion device 19 Within the cushion pocket of the sill section 23. Should the Iconditions be such that the right end of the sliding sill is not held against Vmovement, the sliding `sill sections 27 and 28 will move envases is operative to extend the unit to its original position so that the sill sections are returned to their normal or neutral spaced position.

Assuming now that the car is attached at its right coupler and to a stationary line of cars and a draft force is applied on the left end as shown in FG. 11A, this tends to move the sill section 27' to the left relatively to car attached sliding sill section 2S so that a force is exerted by the draft keys 57 -to compress the shock absorbing unit 5S. As described above in connection with the draft force applied at .the right end, if the force F is less than 409,000 lbs. the shock absorbing unit Si; remains inoperative so that the sill sections Z7 and 28 remain spaced a distance n. Also, if the sliding sill 1S is not restrained the sill sections 27 and 2d move in unison relative to the stationary sill 12 so `that the cushion device It is operative in a manner similarly to that described above in connection with the draft force applied at the right end.

if the draft force F is greater than 460,000 lbs., the shock absorbing unit 5S is contracted by movement of the sill section 27 carrying the shock absorber 5S to the right against the draft keys 57 which are lixed to .the sill section 28 attached to the stationary line of cars. As illustrated in FlG. llA, the device may be contracted or travel a distance d. Thereafter the sill sections 27 and 28 spaced the distance n-d are movable in unison relative to the center sill 12. However, in the event the mass of the stationary cars is such that it restrains movement of vthe sliding sill l, the latter will remain stationary in the position shown in PEG. llA. l the mass connected -to the sliding sill l is such as not to restrain movement thereof, during such movement the stops S5 fixed thereas and abutting the follower d? of the cushion device l@ contracts the latter against the stationary sill stops 47. in this manner the cushion device l? is rendered operative to perform its function. Upon dissipation and transfer of the impact force the cushion springs are operative to return.

Referring now to FlG. 17 the shock absorbing unit S of the present invent-ion is shown employed as a draft gear for connecting a coupler mechanism 3d@ to the center or draft sill Stil of a railway car. The sill Stil may be of substantially conventional construction, such as a 2,-26 center sill, having side walls EQ2 depending from a horizontal top flange, not shown. Extending outwardly from the bottom end of .the side walls 3% are horizontal flanges 393 across which there extends and is detachably fastened a bottom retainer plate, not shown, for supporting the shock absorbing unit 25'3 within the pocket. rhe draft gear pocket 3dS is defined at its ends by longitudinally spaced front and rear draftlugs Silit-Stiel and Suo-3%, lixed to the side walls 3h12-,

Extending between the front draft lugs Shri-364i and abutting the follower surfaces 256 of the shock absorbing device 253 is the coupler shank 3b? which is connected in the well known manner to a yoke 3% which extends through the length of the pocket 365 between the front and rear draft lugs 3l1-3ld and 3% 366 such that the bight portion lili@ thereof contacts the follower surface 256 of the rear friction shoe.

While the shock absorbing unit 25S illustrated is of the friction wedge type having substantially constantforce travel closure characteristics, it is to Abe understood that the shock absorbing unit illustrated in FIGS. l2 to i6 may also be employed. However, as previously described herein, the shock absorbing means Sb of the embodiment of FIGS. 12 to 16 does not have the substantially constant force-travel closure characteristics, otherwise the operation of the shock absorbing units are identical.

Assuming as shown in FIG. 17 the coupler is subject to bud impact, this causes the coupler shank 337 contacting the follower surface 2.56 to move the front shoe rearifi ward toward the rear draft lugs 30o-Silo. The rear friction shoe of which the follower surface 266 contacts the rear stop lugs Silo- 3% is held stationary so that the impact force transmitted to the shock absorbing unit tends to compress the latter. As heretofore described, the rubber biasing pads 272 are constructed to preclude the relative movement until the magnitude of the impact force is a selected value, for example, a value of about 400,000 lbs. Thus, in the event that the impact force is less than 400,000 lbs., the shock absorbing device 25S remains stationary and inoperative.

When the force exceeds 400,000 lbs., the rubber springs 272 are yieldable so that the friction wedge units 2de are transversely displaced and the friction shoes 263 move longitudinally toward each other to a compressed position. ln this manner the friction forces at the contacting faces 267 and En@ and the resisting forces of the rubber springs 272 are operative to absorb a portion of the energy of impact as heretofore described. Upon dissipation of the impact energy the rubber springs 272 are operative to return the friction wedges 268 and friction shoes 263 to their neutral position.

It is, of course, readily apparent that an impact force in draft results in a similar action with the exception that the yoke 30S is operative to compress the unit against the front draft lug 304-394.

What is claimed is:

l. ln a cushion underframe railway car comprising an underframe, a sliding sill, including a pair of longitudinally spaced sill sections movable relatively to each other and said underframe from a spaced neutral position upon application of an impact force, a cushion device interposed between said underframe and said sliding sill and having a predetermined travel, means connecting said sill sections including stress relieving shock absorbing means having a travel less than said travel of said cushion device mounted to interact with said sill sections to relieve the impact stresses through the length of said sliding sill, means rendering said cushion device operative simultaneously with travel of said stress relieving shock absorbing unit, said stress relieving shock absorbing means including means restraining said shock absorbing means against travel below a predetermined magnitude or" impact force whereby said sill sections remain in said spaced neutral position and releasing said shock absorbing device to travel above said predetermined magnitude impact force to permit said sill sections to move relatively to each other from said neutral position, said sections upon termination of the travel of said stress relieving shock absorbing means being conjointly movable relative to said underframe for the remainder of the travel of said cushion device.

2. The invention as defined in claim 1 wherein said Shock absorbing means comprises a plurality of longitudinally spaced friction shoes movable longitudinally relatively to each other between an extended spaced position and a contracted spaced position, and friction wedge means having planar friction faces inclined complementary to the friction faces on said friction shoes, said friction wedge means being disposed on opposite sides of a central longitudinal plane and between the respective pairs of friction shoes, and predeterminately loaded spring means transversely biasing said friction wedge means towards said longitudinal plane so as to maintain said device extended until a shock force longitudinally imposed upon said friction faces exceeds the predetermined load on said spring means.

3. IThe invention as defined in claim 2 wherein said friction shoes and said friction wedges are provided with opposing inclined planar friction faces, said inclined fric- -tion faces and friction wedges being variably inclined so as to provde a substantially constant force travel characteristic.

4. The invention as defined in claim 3 wherein said Y i5 Y friction faces on said friction shoes and said friction wedges are arcuately curved.

5. In a cushion underframe railway car comprising an underframe, a sliding sill mounted for' lengthwise movement on said underframe, a cushion device interposed betweerrsaid sliding sill and said underframe for protecting the lading and the car body from damage, said sliding sill including a pair of sections longitudinally movable relatively to each other from a spaced neutral position upon application of a buff or draft impact, a shock absorbing means for relieving the stresses through theV length of the sliding sill,- said shock absorbing means having a lesser travel than said cushion device and being separate from v said cushion device and mounted for movement with one of said relatively movable sill sections, and interconnecting means mounted for movement with the other of said sill sections interconnecting said sill sections, said interconnecting means embracing said shock absorbing device anden- Y gaging said cushion device so that said shock absorbing means and said cushion device are simultaneously activated to relieve the stresses through the length of said sliding sill during travel of said shock absorbing means, said shock absorbing means including means precluding travel of said shock absorbing means below a predetermined magnitude of impact force and thereby retaining said sill sections in said spaced neutral position, said sill sections being conjointly movable relative to said underframe when said travel of said shock absorbing device is restrained or terminated so that said cushion device is operative to provide lading and car body protection.

6. A shock absorbing device comprising a plurality of 'longitudinally spaced friction shoes movable longitudinally relatively to each other between an extended space position and a contracted position, said friction shoes having pairs of opposing arcuate friction faces arranged on opposite sides of a central longitudinal plane, friction wedge means disposed on opposite sides of said central longitudinal plane between the respective pairs of friction faces having arcuate friction faces inclined complementary to said friction shoe faces, and predetermined loaded spring means transversely biasing said wedge means toward said longitudinal plane so as to maintain saidV shock absorbing means includes a friction energy absorbing arrangement and wherein said means resisting movement comprises resilient means applying a biasing force precluding said friction means from becoming operative until said impact force exceeds a predetermined value.

S. The invention as defined in claim 5 wherein said shock absorbing means includes a plurality of pairs of longitudinally spaced friction shoes movable longitudinally relative to' each other between an extended spaced position and a contracted position, said friction shoes having pairs of opposing sloped friction faces arranged on opposite sides of a central longitudinal plane, and friction wedge means having planar friction faces sloped com- Y plementary to Vsaid friction faces, said friction wedge means being disposed on opposite sides of said central longitudinal plane and between the respective pairs of said opposing friction faces,l and wherein said means resisting movement includes predeterminately load resil- References Cited by the Examiner UNITED STATES PATENTS 1,576,722 3/26 Cotton 213-38 1,648,320 11/27 OConnor 213-38 1,692,689 11/28 OConnor 213-39 1,997,170 4/35 Egan 213-8 2,051,024 S/36 Barrows 213-39 2,064,891' 12/36 Egan 213-8 2,401,905 6/46 Bureau 213-34 2,456,635 12/48 Heater 267-9 2,623,743 12/52 Mulcahy 267-9 2,803,353 8/57 Meyer et al. 213-8 LEO QUACKENBUSH, Primary Examiner. 

5. IN A CUSHION UNDERFRAME RAILWAY CAR COMPRISING AN UNDERFRAME, A SLIDING SILL MOUNTED FOR LENGTHWISE MOVEMENT ON SAID UNDERFRAME, A CUSHION DEVICE INTERPOSED BETWEEN SAID SLIDING SILL AND SAID UNDERFRAME FOR PROTECTING THE LADING AND THE CAR BODY FROM DAMAGE, SAID SLIDING SILL INCLUDING A PAIR OF SECTIONS LONGITUDINALLY MOVABLE RELATIVELY TO EACH OTHER FROM A SPACED NEUTRAL POSITION UPON APPLICATION OF A BUFF OR DRAFT IMPACT, A SHOCK ABSORBING MEANS FOR RELIEVING THE STRESSES THROUGH THE LENGTH OF THE SLIDING SILL, SAID SHOCK ABSORBING MEANS HAVING A LESSER TRAVEL THAN SAID CUSHION DEVICE AND BEING SEPARATE FROM SAID CUSHION DEVICE AND MOUNTED FOR MOVEMENT WITH ONE OF SAID RELATIVELY MOVABLE SILL SECTIONS, AND INTERCONNECTING MEANS MOUNTED FOR MOVEMENT WITH THE OTHER OF SAID SILL SECTIONS INTERCONNECTING SAID SILL SECTIONS, SAID INTERCONNECTING MEANS EMBRACING SAID SHOCK ABSORBING DEVICE AND ENGAGING SAID CUSHION DEVICE SO THAT SAID SHOCK ABSORBING MEANS AND SAID CUSHION DEVICE ARE SIMULTANEOUSLY ACTIVATED TO RELIEVE THE STRESSES THROUGH THE LENGTH OF SAID SLIDING SILL DURING TRAVEL OF SAID SHOCK ABSORBING MEANS, SAID SHOCK ABSORBING MEANS INCLUDING MEANS PRECLUDING TRAVEL OF SAID SHOCK ABSORBING MEANS BELOW A PREDETERMINED MAGNITUDE OF IMPACT FORCE AND THEREBY RETAINING SAID SILL SECTIONS IN SAID SPACED NEUTRAL POSITION, SAID SILL SECTIONS BEING CONJOINTLY MOVABLE RELATIVE TO SAID UNDERFRAME WHEN SAID TRAVEL OF SAID SHOCK ABSORBING DEVICE IS RESTRAINED OR TERMINATED SO THAT SAID CUSHION DEVICE IS OPERATIVE TO PROVIDE LADING AND CAR BODY PROTECTION. 